Audiobook of an early twentieth century catechetical book explaining the doctrine, prayers, and rubrics of the Latin Rite Mass as promulgated at that time. Most of this applies to both the 1962 Mass used today as the Extraordinary Form, and the post-Vatican II Mass used as the Ordinary Form. (It also applies, in broad outline, to earlier Latin Rite Masses and to Masses in other Rites, of course.)
It is particularly interesting to see how the interpretation of certain elements of the Mass has changed over time, even when the basics remain the same.
Part 2 continues the textbook, and Part 3 concludes it, with chapters on High Mass and the Requiem Mass.